This invention is directed to printing apparatus and method for forming an image over a large surface area or walkway such as driveways, fields and/or decks or patios.
This invention generally relates to a marking apparatus and methods and more particularly relates to an apparatus and method for marking a large surface with multiple colors.
It is often desirable to form color images on a large area. For example, children love to draw and write with colored chalk on a driveway. Similarly to drawing with a crayon on a blank piece of paper the child creates drawings, but does not usually have the ability to draw detailed animals, cartoon characters, scenes, and the like. Children like to color in coloring books and print images using a desktop inkjet printer because they can create detailed drawings that are in full color. These activities are fun, and the child does not need the skills of an artist to produce colorful graphic images. When the child attempts to draw the image manually on a surface such as a driveway, the result may be less than satisfactory. Therefore, it is desirable to provide a marking device capable of forming more pleasing images on a large surface such as a driveway.
U.S. Pat. Nos. 5,446,559 and 6,062,686 disclose devices that are designed to print on a small smooth surface such as a sheet of paper on a table or desktop. Because of their compact construction, these so-called handheld devices are not burdened by the size and weight of conventional devices that perform similar functions, such as desktop and large format printers. Furthermore, these handheld devices offer superior flexibility in printing and can be used with over sized media. For example, such handheld devices can print on media that is much larger than used in a desktop printer.
Despite such positive attributes of these handheld devices such as being compact, other less desirable attributes still remain. For example, these handheld devices still require the attention and labor of the user to manually sweep them over an appropriate medium to produce printing on the medium. They are limited in size to a medium that is the size of a sheet of paper or a poster. They are not equipped to print on a rough surface such as asphalt or concrete. To overcome the problems of conveying a hand held device over the surface to be printed a drive mechanism was added. Unlike a desktop printer, the drive mechanism contacts the surface being printed. This creates the problem of contacting the area that has just be printed and damaging the image. In small format printers and printers that are printing several lines of text this is not a problem, but it is a problem for a device printing a large area with a continuous image.
Charles Manning in U.S. Pat. Nos. 6,299,934 and 6,074,693 discloses a global positioning system for controlling a paint spraying system used to apply paint to a large surface such as a road. The systems described in these patents may be suited for locating a paint sprayer used for painting lines on a road to within a few feet, but GPS systems do not possess the positioning precision required for printing an image. Moreover, the paint-spraying device described by Manning does not have the ability to deliver a marking medium to the marking surface with the amount and with the accuracy necessary to form a desirable image.
Therefore, there has been a long-felt need to provide an apparatus and method for suitably marking a large area in a manner which automatically accurately determines the size of the large area to be printed, the distance to the surface and quickly, yet precisely, applies a marking medium uniformly to predetermined portions of the surface and can provide multiple color marking to the surface wherein the surface comprises large surface areas of pavement, wood or other structural composites, or concrete, asphalt, brick, grass or laid carpeting collectively hereinafter referred to as a xe2x80x9cwalkway,xe2x80x9d even though cars or other vehicles may also be driven over same.
A method and apparatus for conveying a portable printing mechanism over a large surface area such as a walkway having a printing means for forming indicia on the surface area is described.
In accordance with a first aspect of the invention, there is provided an apparatus for printing an image on a large surface area or walkway, the apparatus comprising a marking engine responsive to digital signals representing an image for imagewise marking the surface with a color marking solution; i.e. dye or pigment of ink or paint that is in solution or suspension in a liquid, to form a visible image on the surface during an image recording mode; a self-propelled and automatically steered vehicle that supports the marking engine and includes a drive that engages the surface at plural locations for moving the marking engine along the surface. It is preferred to provide the marking engine so that it is located outboard of an area defined by lines connecting the plural locations so that during operation of the marking engine for imagewise marking during the image recording mode the drive does not engage areas of the surface that have been previously imagewise marked and the drive providing movement of the marking engine to position the marking engine at substantially all points to be marked in the area.
In accordance with a second aspect of the invention, there is provided a method for printing an image on a large surface area or walkway, the method comprising imagewise marking the surface with a color marking solution to form a visible image on the surface during an image recording mode of a marking engine that is responsive to digital image signals representing the visible image to be printed; automatically steering a vehicle that supports the marking engine and which includes a drive that engages the surface at plural locations and moving the marking engine relative to the surface, the marking engine being located outboard of an area defined by lines connecting the plural locations so that during operation of the marking engine for imagewise marking during the image recording mode the drive does not engage areas of the surface that have been previously imagewise marked and the drive providing movement of the marking engine to position the marking engine at substantially all points to be marked in the area.
In the preferred embodiment the invention comprises a printing assembly including a housing, a drive and steering mechanism, a power supply, a printer, logic and control unit, and a communications device. The portable printing mechanism can be electronically guided by a removable Erasable Programmable Read Only Memory (EPROM) located in the logic and control unit or it can be guided by transmissions from a remote control device. Alternately, the portable printing mechanism can optically follow a line manually drawn on the driveway or other large surface area.
The portable printing mechanism maps the area to be printed, determines where within the area the indicia is to be formed and the initial starting position, maintains the correct distance between the print head and the surface area to be printed, and maintains the correct spacing of the lines being printed while the indicia is formed.